PJB-2011-306
ROLE OF ABSCISIC ACID (ABA) IN CONTROLLING THE HORMONAL BALANCE AT BOOTING AND GRAIN-FILLING STAGES OF DIFFERENT WHEAT (TRITICUM AESTIVUM L.) CULTIVARS UNDER DROUGHT
SUMERA IQBAL1 AND ASGHARI BANO2*
Abstract
Water shortage seriously influences wheat productivity in various growing regions.The response of two wheat (Triticum aestivum L.) accessions viz., 011417 and 011320 to drought and exogenously applied abscisic acid was determined in a pot study at booting and grain-filling stages to study the role of stress hormone abscisic acid (ABA). Changes in endogenous ABA (bound and free) and the growth promoting hormones i.e. trans zeatin ribiside (t-zr), Indole-3-Acetic Acid (IAA) gibberellins (GA) were monitored. Sampling was done 3, 6 and 9 days after induction of water stress and at 48 and 72 h of re-watering. Marked decreases in t-zr, IAA and GA were found to be associated with an increase in the free and bound ABA content in the leaves under water stress. Sensitive accession 011320, showed the greater decrease in growth promoting hormones and less accumulation of ABA. The inhibitory effects of water stress on plant phytohormonal balance were ameliorated by exogenous ABA application specifically at booting stage and particularly in the sensitive accession 011320. There is a cultivar specific threshold ABA level, which is required to exhibit any significant ameliorating effect under water stress.
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